1. Technical Field
Embodiments of the present disclosure relate to semiconductor device generating a refresh signal.
2. Related Art
A semiconductor system including a semiconductor device may need a periodic signal to control internal operations thereof. That is, the semiconductor system may execute the internal operations in response to the periodic signal generated in the semiconductor system or from an external device. The periodic signal may include pulses which are created to have a uniform cycle. Thus, the periodic signal may be used to execute iterative internal operations of integrated circuits ICs constituting the semiconductor device.
Volatile memory devices, for example dynamic random access memory (DRAM) devices, may lose their stored data as time elapses even though their power supplies are continuously provided. Thus, all memory cells in the DRAM devices should be refreshed within a data retention time corresponding to a maximum time that the memory cells can retain data. Since the refresh operation is periodically executed, the DRAM devices may need a periodic signal to execute the refresh operation.
An operation speed of the semiconductor devices may vary according to a temperature. That is, the higher the temperature, the slower the operation speed of the semiconductor devices. In contrast, the lower the temperature, the faster the operation speed of the semiconductor devices. If the operation speed of the semiconductor device varies according to the temperature, the reliability of the semiconductor devices may be degraded to the point of causing a malfunction.